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World’s first subsea tidal array prepares for operation

Published:  26 May, 2016

The world’s first subsea offshore tidal array, known as the Paimpol-Bréhat Tidal Array developed by EDF, will soon be ready for operation.

The second turbine will soon be deployed onto the seabed and join the first turbine already in place together with GE Power Conversion’s subsea converter. Once completed, the Paimpol-Bréhat Tidal Array is expected to reach a total capacity of 1 megawatt (MW) of power.

The array uses a subsea converter system, supplied by GE Power Conversion, to control the turbine and convert the electricity from AC to high-voltage DC, minimising the energy loss when the power is transmitted 16 km back to shore. It is then converted back to AC by GE’s drive at the onshore facility before being delivered to the grid.

Although 1 MW at Paimpol-Bréhat presents a moderate amount of power, the project sets a precedent for future tidal plants, leading the way towards further offshore arrays.

In the U.K., there are a number of tidal development projects being considered. One of the most notable projects, the proposed Swansea Bay Tidal Lagoon, would be set in the Severn Estuary. The selected location holds the second highest tidal range in the world. Once production starts, it is anticipated that it would reliably generate enough power for approximately 155,000 homes every year for 120 years.

Tidal lagoon projects are built using mature hydro technology. Much like a hydroelectric dam, a tidal lagoon functions by allowing water to enter and leave the lagoon, which in turn drives a turbine within the housing.

Plans are already being made to build another tidal lagoon in Cardiff, which would anticipate providing power for over 1 million homes. Tidal plants can also meet the challenges faced by renewables by providing the industry with a baseload. Since tides are predictable and do not occur at the same time along same stretch of coastline, plants can be regulated and designed to work at full capacities on alternating pre-determined schedules, thus providing constant available power to the grid.

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